What is Sickle-Cell Disease?
Sickle cell disease is an inherited blood disorder. Normally, red blood cells are disc-shaped and flexible. In sickle cell disease, hemoglobin, which is the chemical within red blood cells that carries oxygen around the body, is abnormal. This causes red blood cells to collapse into a crescent or sickle shape. It also causes the red blood cells to be abnormally stiff and fragile. These cells clump together and clog up small blood vessels throughout the body. When blood vessels are blocked by sickle-shaped red blood cells, parts of the body are deprived of oxygen. This can cause severe pain and damage to organs and tissues. Abnormal red blood cells are also destroyed at a high rate, causing a shortage of red blood cells called anemia.
Sickle cell disease is a genetic disorder. If you receive one defective gene from each of your parents, then you will have sickle cell disease. If you only have one defective gene, you are said to have sickle cell trait, but not sickle cell disease. Although you won’t usually have any symptoms, you can pass this gene on to your children. The only way to get sickle cell disease is to inherit two defective genes that cause sickle cell diseases. However, the following factors make a baby more likely to be born with sickle cell disease:
Children who receive one abnormal gene from each of their parents will have sickle cell disease. Children who receive one abnormal gene and one normal gene usually have no symptoms and are said to have sickle cell trait. They can pass their abnormal gene on to their own children, which, if combined with a sickle cell gene from the other parent, will cause a child to have sickle cell disease.
The majority of people with sickle cell disease are of sub-Saharan African descent. Other people at risk for sickle cell disease are those whose ancestors came from South America, Cuba, Central America, Saudi Arabia, India, Turkey, Greece, and Italy.
What are the Symptoms of Sickle-Cell Disease?
Symptoms of sickle cell disease may be noticed as soon as four months of age, or it may go undetected until later in the baby’s first year of life.
Oxygen deprivation is a result of blood vessels that are blocked by the misshapen red blood cells of sickle cell anemia. Periods of acute oxygen deprivation cause severely painful episodes called pain crises. The location of the pain and the types of symptoms depend on what tissues or organs of the body have been deprived of oxygen.
Symptoms of sickle cell disease include:
- Swollen hands and feet
- Pain in:
- Enlarged organs, including:
- Increased risk of infection, especially pneumonia
- Symptoms of anemia, including:
- Severe fatigue
- Shortness of breath
- Heart failure
- Yellowish tone to the whites of the eyes and the skin
- Episodes of sickle cell crisis, including:
- Severe chest pain
- Shortness of breath
- Severe abdominal pain
- Severe bone pain
- In males, painful, prolonged erections of the penis which may result in impotence
Other medical conditions that can result from sickle cell disease include:
- Leg sores
- Gum disease
- Damage to the retina of the eye, resulting in vision loss
- Enlargement of the heart due to chronic anemia
- Heart attack
- Heart failure
- Kidney infections
- Kidney damage and eventual failure
- Bone infections or infarctions
- Gallbladder disease
- Spleen damage and destruction, resulting in an increased risk of certain infections
- Abnormal bone growth
- Delayed puberty
- Learning and behavior problems in children who have had severe, chronic oxygen deprivation of the brain
- Aplastic crisis or red cell aplasia
Sickle cell crisis can be provoked by certain triggers, including:
- Travel to high altitudes
- Drops in oxygen or changes in air pressure that can occur during airplane travel
Diagnosing Sickle-Cell Disease
Diagnosis of sickle cell disease and sickle cell trait can be done through blood testing, using a technique called hemoglobin electrophoresis. Blood tests can be done on children or adults. Many states have laws that require newborn babies to be tested for sickle cell disease before they leave the hospital after birth. Pregnant women can also choose to have their unborn babies tested for the presence of sickle cell trait or sickle cell disease.
- Hemoglobin Electrophoresis: A small blood sample is taken and sent to a laboratory where the percentage of normal and abnormal hemoglobin is measured.
- Sickledex Test: A small blood sample is taken and sent to a laboratory. In the laboratory, a substance called a deoxygenating agent is added to the blood sample. If the deoxygenating agent causes at least 25% of the red blood cells to assume a sickle shape, the test is considered positive for the presence of either sickle cell trait or sickle cell disease. Hemoglobin electrophoresis will need to be done to distinguish between sickle cell trait and sickle cell disease.
- Amniocentesis: In this test, ultrasound is used to locate the fetus and a pocket of the fluid that surrounds the growing fetus. A long, thin needle is used to remove a small amount of amniotic fluid, which is sent to a laboratory for mutation-specific DNA testing.
Treating Sickle-Cell Disease at UVA
There are no treatments to cure sickle cell disease. Instead, treatment is aimed at managing the various symptoms in an effort to minimize complications. The goals of treatment include:
- Managing and preventing acute crisis episodes
- Managing chronic pain
- Managing anemia
- Preventing and treating infections
- Managing complications and organ damage
- Medical support when needed such as:
- Intravenous fluids
- Blood transfusion
- Bone marrow transplant
- Lifestyle changes
Content was created using EBSCO’s Health Library. Edits to original content made by Rector and Visitors of the University of Virginia. This information is not a substitute for professional medical advice.